1-8 완주하지못한 선수

week2/1. 완주하지 못한 선수/Solution.java

@@ -1,7 +1,60 @@
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.Iterator;
+import java.util.Map;
+import java.util.Map.Entry;
+
 /*
     1. 완주하지 못한 선수
     https://programmers.co.kr/learn/courses/30/lessons/42576
 */
 public class Solution {
+    public static void main(String[] args) {
+
+        String[] participant = { "leo", "kiki", "eden" };
+        String[] completion = { "eden", "kiki" };
+
+        System.out.println(solution(participant, completion));
+        System.out.println(solution2(participant, completion));
+    }
+
+    public static String solution(String[] participant, String[] completion) {
+
+        Arrays.sort(participant);
+        Arrays.sort(completion);
+
+        for (int i = 0; i < completion.length; i++) {
+            if (!participant[i].equals(completion[i])) {
+                return participant[i];
+            }
+        }
+
+        return participant[participant.length - 1];
+    }
+
+    public static String solution2(String[] participant, String[] completion) {
+
+        Map<String, Integer> checkerMap = new HashMap<>();
+
+        for (String person : participant) {
+            checkerMap.put(person, checkerMap.getOrDefault(person, 0) + 1);
+        }
+
+        for (String person : completion) {
+            checkerMap.put(person, checkerMap.getOrDefault(person, 0) - 1);
+        }
+
+        Iterator<Entry<String, Integer>> it = checkerMap.entrySet().iterator();
+
+        while (it.hasNext()) {
+
+            Entry<String, Integer> mapEntry = it.next();
+
+            if (mapEntry.getValue() == 1) {
+                return mapEntry.getKey();
+            }
+        }
 
+        return null;
+    }
 }